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Design and Tecnology- map 1 (Smart Materials (Photochromic Pigments…
Design and Tecnology
- map 1
Fossil Fuels
Info
✮Formed over many millions of years and
cannot be replaced
as they run out
✮In 2016 - 55% of the UKs energy is from coal and gas-fired power stations
✮They are
finite
resources
✮When burned,
CO2
is produced
✮Some modern power stations can scrub the exhaust gas emissions by trapping the CO2
✮It is
not
considered an
environmentally friendly
or
sustainable
way of creating energy
Renewable Energy sources
✮Wind turbines
✮Solar Energy
✮Tidal energy
✮Hydroelectric power
✮Biofuel
✮Biomass
CONTROVERSIAL
✮Nuclear
Forces
Tension
✮A
pulling force
applied to
either side
of a material
✮The object
stretches
as it tries to resist being
pulled apart
✮E.g, rope in tug of war, chains on a swing
✮
Tensile strength
- the
ability
of a material to
resist
being pulled apart
Compression
✮A
pushing force
on
either side
of a material
✮It becomes
compressed
when it tries to resists being
squashed
✮E.g, a spring in a suspension system, garlic in a garlic press. These are
being compressed
✮E.g Air in a balloon, spray deodorant in a can. These are also
held under compression
✮
Economical
to store water/ gas under pressure
✮Takes up less room
✮Can control release easily through valves and other devices
✮
Compression strength
- the
ability
of a material to resist being squashed or compressed
Torsion
✮Occurs when a material is
twisted
✮The two end of a material rotate and
twist in opposite directions
✮E.g, wringing out a wet towel, cars on uneven surfaces, boats riding waves
✮Torsional strength - the
ability
of a material to
resit being twisted out of shape
Bending
✮
Tension
and
compression
on
both sides
of its neutral axis
✮E.g, On a seesaw, the beam will bend on both sides over the
fulcrum
(the point of which a lever is placed)
✮Pressure is applied either end with and
upwards
or
downwards
pressure
✮Pressure can be applied to the middle whilst being supported at both ends
✮
Stiffness
- the
abliity
of a material to
resist
being
bent out of shape
Shear Force
✮A
force
acting on an object
perpendicular
to its length
✮E.g, wind pushing on a tree
✮Can also occur when a
material or joint
is being
pulled apart
along
different planes or lines
. The two forces are in
opposite directions
. (Imagine fabric shears cutting fabric)
Battery Voltage
✮Batteries contain
cells
. Each cell is
1.5 volts
✮Each cells has a
positive
and a
negative
Types
✮D
✮C
✮AA
✮AAA
✮PP3
Smart Materials
Thermochromic Pigments
✮Reacts to
temperature change
✮Is a
powder
which is can be added to plastic, fabric and paint
✮Change by heating up, cooling down.
Some
versions are
irreversible
✮Used in flexible thermometers, clothing, temperature indicators, novelty goods, over-heating/over-cooling indicators
Photochromic Pigments
✮Respond to
changes
in
UV light levels
✮Is a
pigment
which is added can be added to fabric, pain and plastics
✮Can be
bonded
to glass
✮Used in novelty goods, paint and clothing
Photochromic Particles
✮Mostly used in silver halides in sunglasses
✮Enable lenses to darken when out in the sunlight, clear when worn inside
✮Can take time to darken lenses/become clear again
✮Over time they loose the ability to go back to clear and eventually stay dark
Shape memory alloy
✮React to
heat or electricity
✮Mid-grey metal with varying thickness
✮
Programmed at 540°C
, deformed and
returned to memory shape
when
reheated to 70°C
✮Used for glasses, dental braces, self-expanding stents used, fire sprinklers
Self-Healing materials
✮Bio-concrete
✮Self-healing polymers
✮They contain
microencapsulated
resin that is released and activated when stress fractures are caused
Quantum Tunnelling Composite
/ QTC
✮Reacts to
pressure
✮Dark polymer with nanoparticles suspended in it (they do not touch each other)
✮Its an
insulator
in its
free state
, a
conductor
when
pressure
is applied
Piezoelectric material
✮Reacts to
movement, stress or electricity
✮Will produce an electrical signal
✮Normally
embedded
into components
✮
Applying
an
electrical signal
will result in a
change of shape
in the material
Litmus Paper
✮Reacts to different levels pH(red-acid, blue-alkaline)
✮Looks like strips of paper
✮Used for soil testing for gardeners, balance in swimming pools, scientific experimentation, wildlife ponds, fish tanks
Output Components
✮LED (Light Emitting Diodie)
✮Lamp
✮Buzzer
✮Speaker
Types of Motion
✮
Linear motion
. One direction along a straight line. (A train on a straight track, runner doing 100m sprint)
✮
Reciprocating motion
. Repetitive up and down or back and forth linear motion. (Needle in a sewing machine, piston moving back and forth in a cylinder)
✮
Oscillating Motion
. A constant movement from side to side along a curved path. (Windscreen wipers, clock pendulum)
✮
Rotary Motion
. Circular motion. ( A ball on a rope being swung in a circle, a merry-go-round as it rotates around its fixed axis)
Levers
✮Changes in magnitude
✮Mechanical advantage -
MA = Load/Effort
✮
Equilibrium
-Caused when the effort and load are equal
✮A lever is a way to gain mechanical advantage(making lifting easier)
Types
Class 1
✮The
load and effort
are on
opposite sides
of the
fulcrum
. The fulcrum can be anywhere between the load and effort
Class 2
✮The
fulcrum is at one end
with the
effort at the opposite
. the
load
is somewhere in the
middle
Class 3
✮The
fulcrum is at one end
, the
load
is
opposite
,
effort
is somewhere in the
middle
✮They have an MA of less than 1 (the force taken > the force they apply
Cams
✮
Eccentric/Circular cam
✮
Pear Cam
✮
Snail Cam
✮
Heart Shaped cam
Follower
✮
Flat Follower
✮Not very accurate from high levels of friction due to surface area in contact. Copes well under load
✮
Knife edged follower
✮Tracks cam movement accurately, low friction but high wear due to fine edge. Not efficient under load
✮
Roller follower
✮Tracks cam movement with some accuracy, friction reduced due to roller. Smooth running, lo wear and efficient under load
Metals
✮
Ferrous metals
are
magnetic
and will
rust
if exposed to moisture without a protective finish.
✮
Low carbon steel/ Mild Steel
✮Construction girders, screws, nails, nuts and bolts, car bodies, bike frames
✮
High carbon steel/Tool steel
✮Garden tools, blades, scissors, wood and metal cutting tools
✮
Cast iron
✮Pots, pans, machine bases and bodies, post boxes, manhole covers
✮
Non-ferrous metals
are
not magnetic
and
do not rust
but the
oxidise
. This causes a metal to
change colour
and go dull with time
✮
Aluminium
✮Pots and pans, car body panels, bike frames, drink cans, foil/ take away trays
✮
Copper
✮Plumbing supplies, electrical cables, bespoke roofing and guttering
✮
Tin
✮Used in plating surfaces to preserve contents, soft solder, alloyed with copper to form bronze
✮
Zinc
✮Mainly used to galvanise steel to prevent rusting, easily die cast or used in alloys
Alloys
✮
Brass
✮Musical instruments, bushes, plumbing fitments, ornate artefacts and hardware
✮
Stainless steel
✮Cutlery, kitchen equipment, medical equipment
✮
High speed steel
✮Cutting tools(drill bits), mill cutters, taps and dies
